Silicone rubber compositions have been used in various fields because of their excellent handling convenience, moldability, heat resistance, after the molding, cold resistance, weatherability, electric insulation, and the like. In particular, the fluorosilicone rubber composition mainly comprising the fluorosilicone raw rubber substantially constituted from the repetition of (3,3,3-trifluoropropyl)-methylsiloxane unit having 3,3,3-trifluoropropyl group as the substituent on the side chain of the backbone of the base polymer has excellent solvent resistance, and therefore, it is widely used as a material or parts in a cargo plane, parts in petroleum-related appliance, and the like, namely, as a material for diaphragm, O-ring, oil seal, and the like.
However, fluorosilicone rubbers are incapable of maintaining the as-molded initial physical properties when they are brought in contact with amines added as an antiaging agent or anticorrosive in gasoline fuel and oil due to cracking of the siloxane backbone. Exemplary such amines include polyether amines, alcohol amines, alkylamines, and the like, and various attempts have been made to improve durability to fuel oil and durability to the amine antiaging agent of these fluorosilicone rubbers.
However, it has been difficult to sufficiently suppress the cracking caused by contact with the amine in the case of the fluorosilicone rubber.